Micro-optic shutter

ABSTRACT

A shutter includes micro-optics having first and second concentrator arrays. A transducer laterally displaces one of the first and second concentrator arrays between transmissive and shuttered modes. In the transmissive mode, the arrays of concentrators are optically aligned to permit electromagnetic energy passing through the first array of concentrators to pass through the second array of concentrators. In the shuttered mode, the electromagnetic radiation is blocked from passing through the second array of concentrators. The concentrators may be compound parabolic concentrators, or lenslets positioned on opposing plates with pinholes printed therethrough. The shutter may increase f-number of radiation passing therethrough, and may be used in a limited f-cone radiation source with shuttering abilities, for example reducing f-cone of radiation output from the radiation source.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/437,085, filed May 19, 2006 , now abandoned which is adivisional of U.S. application Ser. No. 10/325,129 now filed Dec. 20,2002 U.S. Pat. No. 7,049,597, issued May 23, 2006, which claims priorityto U.S. Provisional Patent Application 60/344,130, filed Dec. 21, 2001.The above-identified related applications are hereby incorporated byreference in their entirety as though fully set forth herein.

BACKGROUND

Shutters are known in the art for blocking or allowing transmission oflight. However, current shutters suffer from limited efficiency andlimited function.

SUMMARY

The shutter disclosed herein may provide efficient shuttering incombination with f-number reduction. Such a shutter is for example usedwith a multi-mode or other optical imager, or in a limited f-cone lightsource.

In one embodiment, a micro-optic shutter includes micro-optics havingfirst and second arrays of concentrators. A transducer laterallydisplaces at least one of the first and second concentrator arraysbetween a transmissive mode and a shuttered mode. In the transmissivemode, the arrays of concentrators are optically aligned to passelectromagnetic energy through the micro-optics. In the shuttered mode,the micro-optics blocks the electromagnetic radiation from passingtherethrough.

In one embodiment, a micro-optic shutter includes a first plate forminga first array of pinholes extending therethrough and a correspondingarray of first refractive lenslets adjacent the first array of pinholes.A second plate forms a second pinhole array extending therethrough. Acorresponding array of second refractive lenses are on a second side ofthe second plate and beneath the second pinholes. A transducer laterallydisplaces one of the first and second plates between a transmissive modeand a shuttered mode. In the transmissive mode, electromagnetic energyfocuses through the first and second array of pinholes by refractivepower of the first refractive lenses. In the shuttered mode, theelectromagnetic energy is blocked in transmission through the arrays oflenses by one or both of the plates.

In one embodiment, a limited f-cone light source has a source foremitting radiation and micro-optics positioned adjacent the source andhaving an array of concentrators, for slowing the radiation emitted fromthe light source.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic front view of one multi-mode optical imager;

FIG. 2 is a schematic front view of another multi-mode optical imager;

FIG. 3A is a front view showing compound parabolic concentrators in usewith an optical detector;

FIG. 3B is a perspective view of one array of compound parabolicconcentrators.

FIG. 3C is a perspective view illustrating a shutter with dualconcentrator arrays in a light transmissive mode.

FIG. 3D is a perspective view of the shutter of FIG. 3C in a shutteredmode.

FIG. 4A is a perspective view of a shutter with dual lenslet arrays onfirst and second plates, in a transmissive mode.

FIG. 4B is a perspective view of the shutter of FIG. 4A, in a shutteredmode.

FIGS. 5A and 5B are schematic front views of the shutter of FIGS. 4A and4B within a housing, in transmissive and shuttered modes.

FIG. 6 is a schematic front view showing the shutter and housing of FIG.4A, including an optical detector.

FIG. 7 is a perspective view of a camera employing the shutter of FIGS.4A and 4B.

FIG. 8 is a diagram of a hyperspectral imager, showing exemplarypositions for a shutter of FIGS. 3C-6.

FIG. 9 is a schematic illustration of a multi-channel imaging moduleemploying a shutter of FIGS. 3C-6.

FIG. 10 is a front-view diagram of limited f-cone radiation source.

FIG. 11 is a front-view diagram of the limited f-cone radiation sourceof FIG. 10, with the shutter of FIGS. 3C and 3D.

FIG. 12 is a perspective view of a limited f-cone light source as inFIG. 10, with the shutter of FIGS. 4A-6.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1 shows one common aperture multi-mode optical imager 10 forimaging electromagnetic radiation 12 encompassing two or more wavelengthregions, such as visible light and infrared radiation. Fore-optics 14magnify and direct electromagnetic radiation 12 into a common aperture15 of multi-mode optical imager 10; a focal point 17 of fore-optics 14is seen in FIG. 1. A filter or beam-splitter 16, positioned after thecommon aperture 15, divides electromagnetic radiation 12 into a visiblelight wavelength band 18 and an infrared wavelength band 20. Visiblelight wavelength band 18 is illustratively shown aligned along channel Iand infrared wavelength band 20 is illustratively shown aligned alongchannel II. Channel I and channel II represent, respectively, opticalaxes along which visible wavelength band 18 and infrared wavelength band20 are processed. For example, visible light wavelength band 18 isdirected along channel I through a first field lens 22 and a magnifyingor zoom lens 24 to a first optical detector 26 (or alternatively to acamera that detects visible light wavelength band 18). Infraredwavelength band 20 is directed along channel II through a second lens 28(e.g., a second field lens) and an f-number reducer 30 to a secondoptical detector 32 (or alternatively to a camera that detects long-waveinfrared wavelength band 20). Detection of visible light wavelength band18 and infrared wavelength band 20, by first optical detector 26 andsecond optical detector 32, respectively, may be in the form of a stillimage at a certain point of time (i.e., when a shutter (not shown)opens, and subsequently closes, over common aperture 15 to allowelectromagnetic radiation 12 therethrough) or a stream of video over aperiod of time.

In one embodiment, beam-splitter 16 (e.g., a dichroic beam-splitter 33)divides electromagnetic radiation 12 entering through common aperture 15into visible light and infrared wavelength bands 18, 20, respectively,along channels I and II. First field lens 22 and zoom lens 24 providemagnification capabilities for the visible spectrum imaging of visiblelight wavelength band 18 with first optical detector 26. First fieldlens 22 directs visible light wavelength band 18 traveling frombeam-splitter 16 to zoom lens 24, which focuses visible light wavelengthband 18 onto first optical detector 26; zoom lens 24 facilitates zoomfunctionality to increase or decrease the magnification of the visibleimage captured by detector 26, selectably. First optical detector 26 maybe a CCD or CMOS array, or other detector sensitive to visible light.Infrared wavelength band 20 is directed by second lens 28 traveling frombeam-splitter 16 to optics of f-number reducer 30; f-number reducer 30reduces the f-number of infrared wavelength band 20 prior to secondoptical detector 32. F-number reducer 30 may also be configured toprovide zoom function to increase or decrease the magnification of theinfrared image captured by the detector 32. Beam-splitter 16, firstfield lens 22, zoom lens 24, first optical detector 26, second lens 28,f-number reducer 30 and second optical detector 32 may be combined intoan imaging module 34 that couples with various fore-optics (e.g.,fore-optics 14) to capture and produce final images of electromagneticradiation 12. A housing 36 encases the components of imaging module 34.First optical detector 26 and second optical detector 32 may, of course,be configured for sensitivity to wavebands other than visible light andinfrared as a matter of design choice, depending on the desired imagecharacteristics to be detected by multi-mode optical imager 10. Forexample, other wavebands may include ultraviolet, near infrared andmillimeter waves. These wavebands may be configured and processed inplace of bands 18 and/or 20, for example. Accordingly, multiple imagingmodules 34 may include, for example, channels I and II that processpreselected wavebands, wherein a user “swaps out” imaging module 34 withanother module 34 to capture and image the desired electromagneticspectrum 12.

Housing 36 may be configured with an interface 38 for attachment ofvarying fore-optics 14; such fore-optics 14 may provide a wide field ofview, a narrow field of view, or any range therebetween, as a matter ofdesign choice. In this way, housing 36 may accept fore-optics 14 thatcan be interchanged to alter multi-mode optical imager 10 focal lengthand zoom capabilities, and may thereby form, for example, a microscopeor a telescope having a low f-number. A virtual focal plane 40 offore-optics 14 is thus formed at interface 38, and the location of focalpoint 17 within imaging module 34 may be controlled by the particularoptical properties of fore-optics 14. Furthermore, by this interface 38,various imaging modules 34 having differing imagingcharacteristics—imaging ultraviolet and midwave infrared wavebands (3-5μm), in one example—may be interchanged with fore-optics 14 to providecustom configuration in multiple bandwidth imaging with multi-modeoptical imager 10.

In one embodiment, fore-optics 14 are formed of broad band curvedreflectors 42, such as convex and/or concave mirrors, capturing a realimage 17′ of electromagnetic radiation 12. Reflective surfaces ofreflectors 42 have a number of advantages over traditional refractivelenses when used with multi-mode optical imager 10. First, refractivelenses have indexes of refraction that change drastically betweendiffering wavelengths of electromagnetic radiation, such as visiblelight and LWIR, leading to complex optical designs in order to avoidmisfocus in all of the wavebands. Secondly, the reflective surfaces ofreflectors 42 have a shorter fore-optic length as compared to refractivelenses. Furthermore, the reflective surfaces of reflectors 42 providethe additional benefit of nearly identical optical properties across abroad spectrum of wavebands. The curved reflectors 42 gather theincident visible light and infrared wavebands of electromagneticradiation 12 in a way as to provide the same optical power in bothvisible light and infrared wavebands, while avoiding the focusingproblems of refractive lenses. In one example, the curved reflectors 42may include a concave mirror 44 forming aperture 15, and a convex mirror46. Incident electromagnetic radiation 12 reflects off of concavemirrors 44 and is directed to convex mirror 46, which then focusesradiation 12 through aperture 15 and into imaging module 34. Thefore-optics 14 may for example be a Cassegrain mirrored telescope or aNewtonian mirrored telescope. Those of skill in the art will appreciatethat other broad band fore-optics 14 may be chosen depending on thedesired optical properties of the multi-mode optical imager 10.Electromagnetic radiation 12 is focused by fore-optics 14 at focal point17 forming a real intermediate image plane.

After passing through dichroic beam-splitter 33, infrared wavelengthband 20 encounters f-number reducer 30. In one exemplary arrangement,fore-optics 14 produces an f/4 beam of infrared wavelength band 20 priorto f-number reducer 30; however, this f-number fore-optics 14 is amatter of design choice. F-number reducer 30 provides magnification andf-number reduction so that, for example, second optical detector 32 ofchannel II may be an uncooled microbolometer array 48 to detect infraredwavelength band 20. The f-number reduction of reducer 30 increase theimage signal reducing the effect of secondary radiation (creating noise)within the detected image at second optical detector 32, since secondaryradiation may emanate from, for example, housing 36 of imaging module34. In one embodiment, f-number reducer 30 reduces the infraredwavelength band 20 to have an f-number that is matched to therequirement of uncooled microbolometer array 48 (e.g., f/1). F-numberreducer 30 may include a number of transmissive lenses, shown as a pairof lenses 50 in FIG. 1. As a matter of design choice, f-number reducer30 may also or alternatively include fiber-optics (i.e., fiber opticbundle pulled to a taper), micro-optics located on uncooledmicrobolometer array 48 (see, e.g., micro-optics 58, FIGS. 3A, 3B),and/or other optics to provide magnification and f-number reduction.Lenses 50 of f-number reducer 30 may be fabricated of various opticalmaterials, such as germanium, zinc selenide, calcium fluoride orAMTIR-1.

The production of high fidelity, broadband low f-number optics is knownto be difficult. For this reason, f-number reducer 30 is positioneddownstream from where infrared wavelength band 20 is divided off (i.e.,downstream of beam-splitter 16) such that only infrared wavelength band20 is affected. Additionally, because beam-splitter 16 (i.e., dichroicbeam-splitter 33) and f-number reducer 30 each are designed to conditionnarrow wavebands, these conditioning optics can be relatively small—ascompared to standard conditioning optics of the prior art—furtherlending to the lightweight and compact design of multi-mode opticalimager 10.

A post-processor 52 may also be provided in imaging module 34.Post-processor 52 is coupled with first optical detector 26 and secondoptical detector 32 and may process digital image data representative ofvisible light and infrared wavelength bands captured by detectors 26,32. Analysis by post-processor 52 may provide information about anobject reflecting and/or emitting electromagnetic radiation 12, such asphysical dimensions of the object, thermal energy emitted by the object,imaging characteristics of the object, etc.

FIG. 2 shows one embodiment of multi-mode optical imager 10 with visiblelight wavelength band 18 aligned along channel I and a midwave infraredwavelength band 54 aligned along channel II. Beam-splitter 16 divideselectromagnetic radiation 12 entering through common aperture 15 intovisible light and midwave infrared wavelength bands 18, 54,respectively, along channels I and II. Visible light wavelength band 18is detected by first optical detector 26, and midwave infraredwavelength band 54 travels through second lens 28, which focuses band 54onto second optical detector 32 for detection thereof. A cold shield 56may extend between second lens 28 and second optical detector 32 toshield detector 32 from detecting electromagnetic radiation emittedwithin the housing 36 itself, ensuring accurate detection of the midwaveinfrared wavebands present in electromagnetic radiation 12. The secondlens 28 may also be cooled, further reducing the self emission radiationof the camera from the detected image. A post-processor, such aspost-processor 52, may be coupled with first optical detector 26 andsecond optical detector 32 and may process digital image datarepresentative of visible light and midwave infrared wavelength bandscaptured by detectors 26, 32. Post-processor 52 may analyze reflectedand/or emitted electromagnetic radiation 12 from an object to learninformation about the object.

FIG. 1 and FIG. 2 collectively illustrate another feature provided by amulti-mode optical imager, in accord with one embodiment. Specifically,in the embodiment, midwave band 54 along channel II is “swapped” outwith longwave band 20, FIG. 1, to change which spectra of radiation 12is imaged. By way of example, lens 28, f-number reducer 30, and detector32 (e.g., microbolometer array 48) of FIG. 1 may be removed as a moduleassembly and replaced by lens 28, cold shield 56 and detector 32 (e.g.,a PtSi detector) of FIG. 2 within module 34 as a matter of userpreference.

Exemplary micro-optics 58 are illustrated in FIGS. 3A and 3B. An arrayof filled or solid concentrators 60, preferably forming a series ofcompound parabolic concentrators 62, are positioned adjacent to imagingpixels 64 of uncooled microbolometer array 48 (i.e., second opticaldetector 32). As shown in FIG. 3A, each compound parabolic concentrator62 forms a generally conically-shaped mirror that may be fabricated from(or filled with) various materials, such as high index germanium that istransparent to 7-14 μm infrared radiation and that has a high opticalindex which tends to facilitate detection of infrared wavelength band 20by imaging pixels 64. The optical function of the compound parabolicconcentrators 62 increases the f-cone, and consequently reduces thef-number of the incident infrared radiation at the imaging pixels 64.

Accordingly, compound parabolic concentrators 62 may provide certainadvantages as compared to the prior art, including: permitting use ofsmaller lenses within multi-mode optical imager 10 to produce thedesired f-number at the uncooled microbolometer array 48; and reducingthe size of imaging pixels 64 to increase the signal-to-noise ratio ofmulti-mode optical imager 10, making imager 10 more sensitive to LWIR ofradiation 12. Moreover, by shifting the series of compound parabolicconcentrators 62 directly off of imaging pixels 64 (i.e., adjacent tothe pixels), the infrared wavelength band 20 is effectively “shuttered”,aiding in calibration of multi-mode optical imager 10 (the illustratedconcentrators may also be used generally for shuttering, as describedbelow). Concentrators 60 may be an array of hollow tapered capillaries,e.g., including an inner reflective coating. One or more of fiber optictapers, refractive lens elements and reflective elements may also serveas concentrators 60.

As shown in FIGS. 3C-3D, micro-optics 58 may include a dual array ofconcentrators coupled with a transducer 61, to provide shuttercapability. Concentrators 62 may also be provided on opposing plates(see, e.g., FIGS. 4A and 4B), with one or both of the plates coupledwith the transducer. Referring again to FIG. 3B, compound parabolicconcentrators 62 are for example solid filled concentrators. Filledconcentrators may improve surface reflectivity and increase structuralsoundness of shutter 100, FIG. 3C. Hollow concentrators 62 with areflective coating may alternatively be used.

To illustrate how concentrators may be used in shuttering, considerFIGS. 3C and 3D in more detail. In FIG. 3C, a first array 102 ofconcentrators 62 is positioned over a second array 104 of concentrators62 in a transmissive mode. In transmissive mode, electromagneticradiation 12 entering first array 102 is directed into second array 104.As shown, f-number of electromagnetic radiation 12 entering first array102 is reduced, for example from f/4 upon entry to f/0.55 upon exit fromfirst array 102 and second array 104. Transducer 61 laterally shiftsfirst array 102 (or second array 104), e.g., in the direction of arrow63A, to effect a shuttered mode, as shown in FIG. 3D. In the shutteredmode, light entering first array 102 is blocked from second array 104.The taper of reflective concentrators 62 allows transition betweentransmissive and shuttering modes with minimal movement (enabled bytransducer 61). Shutter 100 is efficient, since transducer 61 need onlyshift first or second array 102, 104 a distance equal to the smallestdiameter of concentrators 62 to achieve shuttering. Transducer 61 is forexample a piezo-electric element that expands and contracts, e.g., undercontrol of imager 10 (e.g., processor 52), to shift first or secondarray 102, 104; control of transducer 61 is for example enabled via acontrol line 65 that applies a voltage to shutter 100. Arrays 102, 104may be positioned adjacent a lens such as first or second lens 22, 28,or in front of a detector element such as first or second detector 26,32 (FIGS. 1, 2), to provide selective shuttering, for example.

Similar to these compound parabolic concentrators 62, shutter 100 may beenabled by dual arrays of hollow tapered capillaries (not shown) with areflective material coated on an inner surface or surfaces of the hollowtapered capillaries. Alternately, shutter 100 may include one or more ofa fiber optic taper, one or more alternate or additional reflectiveelements, and refractive lens elements. Refractive lenses may forexample be made with high-index germanium where infrared radiation istransmitted or shuttered, or with plastic (i.e., plastic filled) whereLED light is transmitted or shuttered.

For example, FIG. 4A shows shutter 106 with first plate 108 and secondplate 110. First and second plates 108, 110 are for example formed of anoptical material having an index of refraction selected for optimumperformance with an intended wavelength or light source (e.g., infrared,LED, incandescent). Unlike shutter 100 using compound parabolicconcentrators 62, shutter 106 uses lenslets 112, which may be etchedinto the optical material of plates 108, 110. Alternately, lenslets 112may be printed onto glass plates 108, 110.

In particular, first plate 108 includes a first array of lenslets. Inthe embodiment of FIG. 4A, the concentrators are refractive lenslets112. Although lenslets 112 may be lightweight and thin; to furtherreduce the weight and volume, Fresnel lenslets may be used. Otherdiffractive lenslets may also be combined with plates 108, 110, as amatter of design preference. First array of lenslets 112 (hereinafter,“first array 114”) is on a top or front face 116 of first plate 108,each lenslet 112 over a pinhole. A first array of the pinholes(hereinafter, “first pinholes 117”) is aligned with first array 114.First plate 108 is positioned opposite second plate 110. Second plate110 includes a second array of pinholes (hereinafter, “second pinholes118”) and a second array of lenslets 112 (hereinafter, “second array120”) aligned with second pinholes 118 on a bottom or back face 122 ofsecond plate 110. First and second pinholes 117, 118 are for exampleprinted on glass, plastic or metal plates 108, 110. Lenslets 112 may beglass or plastic lenses printed upon plates 108, 110.

In FIG. 4A, shutter 106 is shown in transmissive mode. Electromagneticradiation 12 entering first array 114 is focused through first pinholes117, second pinholes 118 and out second array 120. The f-number at firstarray 114 is for example higher than the f-number at second array 120,allowing more light to be focused upon a detector, lens or camera sensorbehind second array 120. In one embodiment, radiation 12 is focusedthrough first pinholes 117 and second pinholes 118 by refractive powerof first array 114, and slowed (e.g., focused into a more parallel beam)exiting second array 120, by refractive power of the second array 120.The f-number at first array 114 is for example higher than the f-numberat second array 120, allowing more light to be focused upon a detector,lens or camera sensor behind second array 120. Transducer 61 againoperates to move first plate 108 laterally (arrow 63A).

Transducer 61 may optionally, or additionally, move second plate 110. Byshifting first plate 108 (or second plate 110) by a transition distanced_(T), which is approximately equal to the diameter d_(P) of onepinhole, transducer 61 switches between transmissive and shutteredmodes. Shuttering may be achieved by shifting first plate 108 by d_(T)in the direction indicated by arrow 63A, or opposite arrow 63A. Theshort distance d_(T) required to move first plate 108 or second plate110 lends to a quick and very efficient shutter.

In shuttered mode, shown in FIG. 4B, radiation 12 entering first array114 and focused through first pinholes 117 is blocked from enteringsecond pinholes 118 and second array 120. To switch back to transmissivemode, transducer 61 moves first plate 108 laterally by transitiondistance d_(T). Lateral movement of first plate 108, for example, in thedirection of arrow 63B by transition distance d_(T), (approximatelyequal to the diameter d_(P) of one pinhole) switches from shuttered modeto transmissive mode, as shown in FIG. 4A. The short distance d_(T)required to move between modes facilitates quick and efficientshuttering.

For clarity of illustration, FIGS. 4A and 4B show plates 108, 110 (andthus pinholes 117, 118) separated from one another; however, it will beappreciated that plates 108, 110 may contact one another. For example, apinhole 117 contacts plate 110 when shutter 106 is in shuttered mode,and “contacts” a pinhole 118 when shutter 106 is in transmissive mode.Additionally, it will be appreciated that shutter 106 may have a singlearray of pinholes. For example, shutter 106 may have one pinhole array(e.g., plate 108 with pinholes 117) in communication with transducer 61,with compound parabolic concentrators 62 (see FIGS. 3B-3D) in place oflenslets 112). Transducer 61 displaces the pinhole array to transmitlight through the pinholes and through an aperture, for example (see,e.g., apertures 126A, 126B in FIGS. 5A-6), without transmission througha second pinhole array.

Shutter 106 may be provided within a housing 124, schematically shown inFIGS. 5A, 5B. Housing 124 includes one or more regions of aperture 126,shown in FIGS. 5A, 5B as top aperture 126A and bottom aperture 126B.Housing 124 may be provided within an imager 128, e.g., multi-modeoptical imager 10, as shown schematically in FIG. 6. As shown in FIG. 6,when in transmissive mode, shutter 106 focuses incoming radiation 12 ona detector 130, which may correspond to detectors 26 or 32, describedabove. In transmissive mode, shutter 106 may also limit radiationimpinging upon detector 130. For example, by directing light throughpinholes, less overall light may reach detector 130 than if radiation 12were allowed to strike detector 130 without intervening plate(s) andpinholes. Alternately, housing 124 and housing 36 (FIG. 2) may be oneand the same, shutter 106 replacing or enhancing micro-optics (e.g.,micro-optics 58) located on uncooled microbolometer array 48. It will beunderstood that shutter 100 may be substituted for shutter 106 asillustrated in FIGS. 5A-6.

An exemplary multi-mode optical imager 150, having optical componentssimilar to those of multi-mode optical imager 10 and shutter 100/106, isschematically shown in FIG. 7. Multi-mode optical imager 150 forms acamera 152, for example for capturing and imaging visible light andinfrared wavelength bands. Fore-optics 14′ are shown coupled to housing36′ of imaging module 34′ (represented by a dotted line). Shutter100/106 is shown encased in housing 36′, with first and second plates108, 110 and their respective components positioned between fore-optics14′ and imaging module 34′. Transducer 61 is shown in connection withelectronics 154 (via control line 65) and coupled with second plate 110.Transducer 61 may be positioned elsewhere within housing 36′. Imagingmodule 34′ may encase internal optics such as image splitter 16, firstoptical detector 26, f-number reducer 30 and second optical detector 32of FIG. 1, for capturing visible light wavelength band 18 and infraredwavelength band 20, likewise of FIG. 1, to process and/or imagemulti-mode images. In one embodiment, shutter 100/106 is housed in frontof these internal objects, within imaging module 34′.

Shutter 100/106 is for example actuated as described with respect toFIGS. 3C-5B. In transmissive mode, shutter 100/106 initiates imagecapture by allowing visible light and infrared wavelength bands to enterinto imaging module 34′. Shutter 100/106 may be used for periodiccalibration of the visible and IR detector arrays, or may be, forexample, installed only in an IR channel (e.g., channel II, FIG. 1) toallow for calibration of the IR channel alone. Electronics 154 (e.g., amicroprocessor) couple with first optical detector 26 and second opticaldetector 32 to process the detected images in visible light wavelengthband 18 and infrared wavelength band 20, such that a visualrepresentation of the detected images may be shown, for example, on adisplay screen 156. Display screen 156 may for example be an LCD displaypositioned on optical imager 150, though those skilled in the art willappreciate that display screen 156 may also be positioned remote toimager 150 as a matter of design choice. Display screen 156 may likewiseshow data related to shutter 100/106, for example, a shutter speedselected with input buttons 158. Input buttons 158 may also bepositioned on optical imager 150 and coupled with electronics 154, suchthat user selections on input buttons 158 may guide image capture byoptical imager 150 and the characteristics and functions of displayscreen 156 (e.g., display of images of visible light wavelength band 18and/or infrared wavelength band 20, overlay a map to determine locationof object emitting and/or reflecting electromagnetic radiation 12detected by optical imager 150, etc.).

When provided within or coupled with imaging module 34, shutter 100/106may become a core component for calibrating and shuttering multi-modeoptical imagers. Shutter 100/106 may be provided with hyperspectral andother imagers described in U.S. Pat. No. 7,049,597, which isincorporated herein by reference. For example, shutter 100/106 may beused in combination with distance finders, laser rangers, targetinglasers, beam splitters or reflectors, GPS, rate sensors, militaryoperations, software and other applications described in U.S. Pat. No.7,049,597.

For example, in one embodiment, shutter 100/106 may be used incombination with a hyperspectral imager as part of imaging module 34.FIG. 8 shows one such hyperspectral imager. Hyperspectral imager 66provides spectral separation of visible light wavelength band 18 into adiffracted spectrum band 68, for high precision sensing of the visiblelight wavelength portion of the electromagnetic radiation 12 given offby an object in the field of view of multi-mode optical imager 10.Hyperspectral imager 66 includes: a collimator 70 that collimatesvisible light wavelength band 18 after splitting at beam-splitter 16; adispersing element 72, such as a diffraction grating or a prism, thatseparates various wavelengths of radiation within visible lightwavelength band 18 into diffracted spectrum band 68; and an imaging lens74 that focuses diffracted spectrum band 68 onto a visible detectorarray 76 to capture and image diffracted spectrum band 68 of visiblelight. Shutter 100/106 may provide shuttering and calibration at variouspositions, for example before (position A) or after (position B) commonaperture 15 or in front of detector array 76 (position C) ormicrobolometer array 48 (position D). Shutter 100/106 may likewise serveas f-number reducer 30. Detector array 76 may be one-dimensional,providing spectral separation of diffracted spectrum band 68, or may betwo-dimensional, providing both spectral and spatial separation of band68. In a similar way this may be applied to hyperspectral imaging in theinfrared bands using an infrared detector array in place of the visiblelight detector array. Those skilled in the art appreciate thathyperspectral imager 66 may further include a slit or array of microlenslets (e.g., at location 19) that reduce the field of view thereof. Apost processor 78 may also be coupled with detector array 76 foranalysis of the captured diffracted spectrum band 68 (post processor 78may for example be incorporated with or within processor 52, FIG. 1).For example, such analysis by post processor 78 may include examiningthe particular visible light wavelengths detected to aid in determiningthe chemical composition of an imaged object. Processor 78 may furthercontrol transducer 61 via control line 65. Additional information can beobtained about the imaged object by coupling second optical detector 32detecting infrared wavelength band 20 to post processor 78. By, forexample, overlaying the detected image of infrared wavelength band 20with the detected image of visible light wavelength band 18, the visualpicture of the imaged object may be obtained while also viewing the heatsignature (i.e., infrared radiation) emitted and/or reflected by theobject. The overlaying of bands 18, 20 provides the feature of, forexample, visual and thermal imaging (i.e., visual picture and heatsignature). Visual and thermal imaging may be used to provide day/nighttarget detection. Thus, with multiple waveband imaging, superior targetdetection is achieved because a range of ambient conditions (e.g.,high/low levels of visible light) will not defeat the imaging abilitiesof imaging module 34.

To further control hyperspectral imagery, imaging module 34 may beprovided with input buttons 80, similar to input buttons 158 of FIG. 6,and a controller 82, such as a microprocessor, to direct the processingby post-processor 78 according to user input to buttons 80. Controller82 may also control detector array 76 (and/or other detectors of imagingmodule 34), including, for example, shuttering operations of imager 34(by controlling shutter 100/106). Controller 82 may be incorporated withor within post-processor 78 as a matter of design choice. If a userdesires to have information about an imaged object, one or more inputbuttons 80 may be depressed to instruct controller 82 to direct theprocessing by post-processor 78 of an image captured by hyperspectralimager 66. For example, post-processor 78 may be pre-programmeddigitally with automatic target recognition (ATR) to identify a certainobject (e.g., a tank) depending on the types of visible spectral bandswithin visible light wavelength band 18 that are detected by detectorarray 76. Upon the user depressing one or more of input buttons 80,controller 82 directs hyperspectral imager 66 to detect the visiblelight wavelength band 18, and second optical detector 32 to detect theinfrared wavelength band 20, such that the images may be viewed on, forexample, a display screen (i.e., display screen 156). The image may, ofcourse, include still pictures or a stream of video pictures (e.g.,MPEG) captured by multi-mode optical imager 10. Further identificationor enhanced recognition of imaged objects may be achieved by processingthe image detected by second optical detector 32 and, for example,overlaying the image with the image captured by hyperspectral imager 66.Likewise, a user wishing to check or adjust shutter operations, such asshutter speed, may do so by pressing one or more associated inputbuttons 80.

Imaging module 34 is shown in FIG. 9 to have channel I along whichvisible light wavelength band 18 is aligned, channel II along which alongwave infrared wavelength band 84 is aligned, and channel III alongwhich midwave infrared wavelength band 54 is aligned. Electromagneticradiation 12 is first split by beam splitter 16 into visible lightwavelength band 18 and infrared wavelength band 20; infrared wavelengthband 20 travels to a second beam splitter 86 dividing infraredwavelength band 20 into long-wave infrared wavelength band 84 andmidwave infrared wavelength band 54. Distance finder 200, in the form ofoutput and input laser rangers 304, 306 in FIG. 9, sends and receives,respectively, laser signals 308 partially along channel I with visiblelight wavelength band 18. Visible light wavelength band 18 encountersfirst field lens 22 and one or more zoom lenses 24 to focus a visibleimage of radiation onto first optical detector 26, in a similar fashionto multi-mode optical imager 10 of FIG. 1. Along channel III, midwaveinfrared wavelength band 54 travels through second lens 28, whichfocuses band 54 onto an MWIR detector array 88 (e.g., an InSb array) fordetection thereof. A cold shield 56 extends between lens 28 and the MWIRdetector array 88, as described in FIG. 2. In channel II, shutter100/106 shutters and reduces f-number of the long-wave infraredwavelength band 84, for example to match the f-number of the secondoptical detector 32, such as uncooled microbolometer array 48. For easeof illustration, not all components of shutter 100/106 are shown in FIG.9.

Shutter 100/106 may also be used in connection with lenses 22, 24, 28 orat aperture 15. An output laser ranger 304, an input laser ranger 306,first optical detector 26, MWIR detector array 88 and uncooledmicrobolometer array 48 may all couple with a controller or processor90, as shown. Processor 90 may perform post-processing on imagesdetected by first optical detector 26, second optical detector 32, andMWIR detector array 88 for display for a user on a display screen 94coupled with processor 90. Processor 90 may also process data fromoutput laser ranger 304, and input laser ranger 306, and utilize (a) aGPS determined location of imaging module 34 relative to the earth, and(b) sensed data from orientation sensors (e.g., pointing and compasssensor 302) to determine the location of target object 204. A wirelesstransmitter 92 and antenna 93 may couple with processor 90 to transmitcaptured image data, distance from target object data, GPS location ofimaging module 34, and/or location of target object 204, to remotereceivers, such as an intelligence command center at a military base, asfurther described in U.S. Pat. No. 7,049,597.

FIGS. 10-13 illustrate use of shutters 100, 106 in a limited f-conelight or radiation source 400. FIG. 10 is a simplified diagram oflimited f-cone light or radiation source 400. Source 400 includes aninternal light or radiation source 402, shown disposed within a housing404. Internal source 402 is for example an LED, a filament, a blackbodyemitter, an incandescent filament or a flat plate emitter. A powersource 406, for example a battery, powers internal source 402. An array408 of concentrators, for example compound parabolic concentrators 62,captures radiation 12 from internal source 402 for quasi-collimatedtransmission through an aperture 410. Array 408 increases f-number ofradiation 12 from internal light source 402 to aperture 410. F-number isfor example increased (slowed) from about 0.55 at a first end 412 ofconcentrators 62 to about 4.0 at a second end 414 of concentrators 62.Radiation 12 thus leaves limited f-cone source 400 as a more collimatedbeam (e.g., having a smaller f-cone than radiation emitted from source402).

As shown in the simplified view of FIG. 11, f-cone reduction may becombined with the efficient shuttering capabilities described hereinabove. In particular, FIG. 11 shows concentrator array 408 of FIG. 10,along with a second concentrator array 416. One or both of arrays 408,416 couple with transducer 61 to form shutter 100. Power source 406couples with transducer 61, e.g., via connection 415, to move array 408and/or array 416 laterally. Transducer 61 is for example apiezo-electric element that expands and contracts to move array 408 or416 responsive to voltages supplied by connection 415. Control line 65may connect with a processor (not shown) that controls shutteringresponsive to user commands. Switching between shuttered andtransmissive modes is achieve by moving array 408 or array 416 to theright or left (as depicted in FIG. 11) by a distance equal to the widthw of first end 412. The transition distance d_(T) between transmissivemode (shown) and shuttered mode is thus about equal to width w.

FIG. 12 provides a perspective view of a limited f-cone light source 500with shutter 106 (for ease of illustration, shutter 106 is notspecified, however, given the above discussion, it will be understoodthat shutter 106 may include first and second plates 108, 110; lenslets112 arranged in first and second arrays 114, 120; first and secondpinholes 117, 118 and transducer 61, as described with respect to FIGS.4A and 4B). When in transmissive mode (shown), shutter 106 receivesradiation 12 from an internal light source 502 and directs radiation 12out of a housing 504, via an aperture 506. Power source 508 powerstransducer 61 (via connection 509). For example, responsive to inputfrom a control line 511, power source 508 provides a voltage viaconnection 509, causing transducer 61 to shift plate 108 or 110. In theembodiment of FIG. 12, shuttering is achieved when transducer 61 movessecond plate 110 laterally (left or right) by a distance equal to thediameter d_(P) of a pinhole 116 (of first pinholes 117 or secondpinholes 118). User interface buttons 510 may be provided, for exampleto allow selection of shutter speed or to turn limited f-cone lightsource 500 on or off. For ease of illustration, certain connectionsbetween user interface buttons 510 and power source 508 and transducer61 (and between power source 508 and internal light source 502) are notshown. Likewise, it will be appreciated that although FIG. 12 showslinear arrays 114, 120 with linear pinholes 117 and 118, two-dimensionalarrays of lenslets or other concentrators may be utilized with lightsource 500. In addition, it will be understood that shutter 106 maylimit or slow radiation passed from light source 502 through aperture506 without utilizing shuttering mode, by focusing through pinholes.

Since certain changes may be made in the above systems without departingfrom the scope hereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing be interpreted asillustrative and not in a limiting sense. It is also to be understoodthat the following claims are to cover certain generic and specificfeatures described herein.

1. A micro-optic shutter, comprising: micro-optics having a first arrayof concentrators and a second array of concentrators; and a transducerfor laterally displacing at least one of the first and secondconcentrator arrays between a transmissive mode and a shuttered mode,wherein in the transmissive mode the arrays of concentrators areoptically aligned to pass electromagnetic energy through themicro-optics, and wherein in the shuttered mode the micro-optics blocksthe electromagnetic radiation from passing therethrough.
 2. The shutterof claim 1, the concentrators of the first and second arrays comprisingreflective concentrators each having a compound-parabolic shape.
 3. Theshutter of claim 1, the micro-optics comprising an array of hollowtapered capillaries.
 4. The shutter of claim 3, each hollow taperedcapillary comprising a reflective coating on an inner surface thereof.5. The shutter of claim 1, the micro-optics comprising one or more of: afiber optic taper and reflective elements.
 6. The shutter of claim 1,further comprising a housing encasing the micro-optics and thetransducer, except for at least one region of aperture.
 7. The shutterof claim 1, the transducer comprising a piezo-electric elementresponsive to a control signal to displace the first or the second arraylaterally between the transmissive mode and the shuttered mode.
 8. Theshutter of claim 1, one or both of the first and second arrayscomprising a plate for supporting the array, the plate coupled with thetransducer.
 9. The shutter of claim 1, the concentrators of the firstand second arrays comprising refractive concentrators, the micro-opticscomprising: a first plate forming a first array of pinholes extendingtherethrough, the first array of concentrators supported on the firstplate and over the first pinhole array; and a second plate forming asecond array of pinholes extending therethrough, the second array ofconcentrators supported on the second plate and under the second pinholearray; wherein the first and second plates are aligned in thetransmissive mode and unaligned in the shuttered mode.
 10. The shutterof claim 9, wherein the transducer laterally displaces the first or thesecond plate by the diameter of one of the pinholes, to shift betweenthe transmissive and the shuttered modes.
 11. A micro-optic shutter,comprising: a first plate forming a first array of pinholes extendingtherethrough and a corresponding array of first refractive lensletsadjacent the first array of pinholes; a second plate forming a secondpinhole array extending therethrough and a corresponding array of secondrefractive lenses on a second side of the second plate and beneath thesecond pinholes; and a transducer for laterally displacing one of thefirst and second plates between a transmissive mode and a shutteredmode, wherein, in the transmissive mode, electromagnetic energy focusesthrough the first and second array of pinholes by refractive power ofthe first refractive lenses, and, in the shuttered mode, theelectromagnetic energy is blocked in transmission through the arrays oflenses by one or both of the plates.
 12. The shutter of claim 11, thefirst and second plates comprising glass.
 13. The shutter of claim 11,the first and second array of lenses being printed upon the first orsecond plates.
 14. The shutter of claim 13, the printed lensescomprising plastic.
 15. The shutter of claim 1, the micro-opticscomprising one or more refractive lens elements.
 16. The shutter ofclaim 1, wherein the micro-optics are positioned adjacent a source foremitting radiation in a limited f-cone light source; the transducershifting one of the first and second concentrator arrays between thetransmissive mode and the shuttered mode, to shutter the source.
 17. Theshutter of claim 16, wherein in the transmissive mode the arrays ofconcentrators are optically aligned to permit radiation from the sourcethat passes through the first array of concentrators to pass through thesecond array of concentrators, and wherein in the shuttered mode theradiation is blocked from passing through the second array ofconcentrators.
 18. The shutter of claim 8, the source for emittingradiation selected from the group of an LED, a filament, a blackbodyemitter, and incandescent filament and a flat plate emitter.
 19. Theshutter of claim 8, the concentrators of the first and second arrayscomprising reflective concentrators.
 20. The shutter of claim 12 one orboth of the first and second array of lenses being etched into theglass.